The aim of this study was to investigate the effects of supplementation of iron and zinc, alone or combined, on iron, zinc and vitamin A status in primary school children. The study was a randomized double-blind clinical trial in which 79 primary school children, 11 year of age, were randomly supplemented for 4 months with iron (20 mg day(-1)), zinc (20 mg day(-1)), or iron+ zinc (20 mg of each day(-1)). Serum zinc significantly increased in all supplemented groups. Compared with iron alone, zinc supplementation and zinc plus iron were associated with higher serum zinc and plasma ferritin levels. Zinc supplementation resulted in a decrease in serum ferritin. Children deficient in zinc at the beginning of the study had a significantly greater increase in serum zinc than did children with adequate serum zinc. Four months after supplementation, hemoglobin remained unchanged in all supplemented group. Plasma retinol levels decreased in all supplemented groups. Supplementation with iron plus zinc improved serum zinc and plasma ferritin. However, since plasma retinol levels decreased as a result of supplementation, more studies are needed on the matter.